I don't think so. All of the bugs you attract weigh the car down too much. Either that or a yellow jacket gets in the car and stings you, after being attracted to what it thinks is a big flower, and you have to pull over!

My wife had an MY Z06. I know.

 

Sounds like you were jealous of your wife’s Z06?

You need to sit down and talk this through with your wife. It's not good to hold things in.

 

I don't think 3 gallons mixed in would be noticeable,and it's not worth the difference in cost to try to run regular in a 50g car.

 

As others have said, the computer will adjust to it. I just wouldn't be nailing it at all until I let it go to empty, re-filled it with 93 & let it re-adjust to where it was. I would wait about a half a tank to be safe. That's what I did when the stupid guy put 89 in my Vette when I clearly said 93. Lets just say that was the last time anyone put gas in my Vette other than myself.

 

What octane does GM use when rating the '08 car at 430-436 hp? Regular, mid, or premium? I only use 93 here in S FL, but I know I won't be able to get it in a lot of states. My car has a Chuck COW tune for 93, so I guess I will be seeing less hp at any lower octane number.

 

Hey Guys.....

OCTANE IS OF THE HIGHEST IMPORTANCE.....after I've tuned your car for 93...You must use it always.....

If for some reason you don't get the right octane for whatever reason, DO NOT DRIVE THE CAR AGGRESSIVELY until you flush (use up) the lower octane.

I've modified the tune to be able to pull significant amounts of timing if necessary, but as quick as it is, it's not instant. It will fix itself after some pinging and should not continue, but the only way to fix itself is for it to ping first.....Keep it to a minimum.

MY ADVICE IS ALWAYS THIS: If I've tuned your car for "x" octane..You must use it. Simple. If it is not available, drive responsibly untill you fill your tank completely with the correct fuel.

For ABUSIVE driving, TRACK USE, or EXTREME HOT SUMMERS, BUY TORCO OCTANE BOOSTER (www.TORCO.com) and keep a few cans in the garage for extra performance and saftey.

This is good advice....Print this and keep it in your glove box.
Chuck CoW

 

And can't you just add some octane booster if you realize you've made a mistake?

 

I guess when I make my trip around the country I will have to carry some Torco with me to boost the lower octanes some states have.

 

Wow chuck your all over the place arnt you! Thanks for the TORCO tip, its certainly a good idea to have a couple bottles in reserve.

 

If not racing , reg will do fine. !2,233 mi & counting!

 

another testimony to the generals quality of the product,all my gm vehicles run on low octane with noooo spark knock,try that in a ford.i know i own lots of both products ,just remember your high compression in your vette does require the higher octane for the performance you bought it for,the computer will just compensate for low octane by retarding timing,fuel adjustments etc,i would not want to rely on those safety features all the time .just my 2 cents,inthe old days you just melted pistons,blown head gaskets ,spark plug electrodes go missing out the exaust i think.etc

 

The 2005-08 Mustang GT requires 87 octaine. Same goes for my 2000 Expedition Eddie Bauer 5.4L (I used to own)

By the way... Good post though, I wasn't trying to knock you or anything. I just happen to know those two Fords because I owned one & my younger brother owns the 06' Mustang GT.

 

Same thing happened to me when I first got the car… told the guy 93, and didn't pay attention and when I got the credit card receipt I found out I just paid for 87!!! Good thing I was just putting around anyway and not doing any fast acceleration or really high RPM's and was religiously following the easy going first 500 mile break-in period anyway and found comfort in the manual that the car adjusts for the fuel. Whew!

 

I filled up with 87 by accident once and the car ran like crap. I don't understand how some people run 87 and don't notice any difference. I use 93 regularly.

 

Some of you guys are misinformed. (Notice I don't say wrong.) Now, our Corvette's call for higher octane fuel. So use it. But don't think that putting high octane fuel in your Honda is "better."

As a disclaimer, I have a framed piece of paper on my wall that says I gradjamatated from PSU with a degree in Chemistry, concentrating my senior year in fuel sciences.

Here's the deal. Technically, an octane rating measures the proportion of isooctane to heptane in a fuel. But as a practical matter, a fuel's octane rating relates to how much energy it takes to ignite that fuel.

The higher the octane number, the more energy it takes to ignite the gas.

Unless your car is explicitly designed to run on high octane gas (read your car's manual), using a high octane gas will NOT give your car better mileage. That's because the rating refers to how much energy it takes to ignite the gas, not directly to how much energy the gas puts out.

Also, using higher octane fuel will NOT give your car more power. Once again, unless your car is explicitly designed for high octane gas, using a high octane gas will not improve the power output of your engine. Again, the octane rating relates to how much energy it takes to ignite the gas, but NOT directly to how much energy the gas puts out.

Of course, with anything, there are exceptions to the rule. One exception is with engines designed for high octane gas. In that case, using high octane gas WILL improve performance and mileage. The reason has to do with the compression and ignition timing characteristics of the engine. Those specially designed engines will only perform efficiently with higher octane gas. Most engines are not designed this way.... so what I'm trying to say is your regular cars don't require high octane fuel. Engineers designed the engines. They know what they're doing (for the most part). When they say to fill up with 87, then use 87.

The second exception is if your car has a lot of engine knocking or pinging. This is a sign that the gas is not igniting when it should. This reduces the power and efficiency of the engine. In this case, use a higher octane gas and see if it helps. (And by higher, I mean 89 and not 92.)

The octane rating of gasoline tells you how much the fuel can be compressed before it spontaneously ignites. When gas ignites by compression rather than because of the spark from the spark plug, it causes knocking in the engine. Lower-octane gas can handle the least amount of compression before igniting. The compression ratio of your engine determines the octane rating of the gas you must use in the car, which is why we should really follow the advice of the engineers who designed our engines.

The name octane comes from the following fact: When you take crude oil and "crack" it in a refinery (technical term is fractional distillation), you end up getting hydrocarbon chains of different lengths. These different chain lengths can then be separated from each other and blended to form different fuels. For example, you have heard of methane, propane and butane. All three of them are hydrocarbons. Methane has just a single carbon atom. Propane has three carbon atoms chained together. Butane has four carbon atoms chained together. Pentane has five, hexane has six, heptane has seven and octane has eight carbons chained together.

It turns out that heptane (7) handles compression very poorly. Compress it just a little and it ignites spontaneously. Octane handles compression very well -- you can compress it a lot and nothing happens. Isooctane is assigned an octane number of 100. It is a highly branched compound that burns smoothly, with little knock. On the other hand, heptane is given an octane rating of zero. It is an unbranched compound and knocks badly.

So, as you may have already guessed, 87-octane gasoline is gasoline that contains 87% octane and 13% heptane (or some other combination of fuels that has the same performance of the 87/13 combination of octane/heptane). It spontaneously ignites at a given compression level, and can only be used in engines that do not exceed that compression ratio.

And have you ever gone up to a pump and seen that mathematical formula [(R+M)/2] on one of those inspection stickers? One value is the research octane number (RON), which is determined with a test engine running at a low speed of 600 rpm. The other value is the motor octane number (MON), which is determined with a test engine running at a higher speed of 900 rpm. If a gasoline has an RON of 94 and a MON of 84, then the posted octane number would be the average of the two values: 89.

Whew, that was a great review. I'm now going to pick up my girlfriend, go to a bar, and forget everything I just said.

--- Ross

 

I would always use premium in mine but I wouldn't worry too much if I put 87 in it by mistake. Usually I screw up the other way and end up putting premium in my Envoy Denali by mistake.

 

Wow I almost did the same as you. I was about to drive away and just happened to look to see how many gallons it took and I was like WHOA!
Thank goodness you took it easy You were lucky on that one

 

I see you're in my neighborhood and was trying to PM you but got this message:

Vetteoholic has exceeded their stored private messages quota and can not accept further messages until they clear some space.

So clear out that box and make room for my message!

 

Oh yeah that's right 50 is the max, I forgot. Thanks for telling me. I'll clear them right now.

 

Ross, very good post.
Just a few tweaks though.

The octane rating is a reference scale to measure spark ignition (SI) knock and has been estabilished by arbitrarily selecting two primary reference fuels. They are isooctane (2,2,4 trimethyl pentane) which has been arbitrarily assigned an "octane rating" of 100 and n-heptane which has been arbitrarily assigned an "octane rating" of 0. The "octane rating" of a fuel is found by comparing its' knock intensity with various mixtures of n-heptane (or heptane) and isooctane. So an octane rating of 93 means a fuel has the same knock intensity in a standard CFR engine (google "astm CFR engine", you can vary compression ratio while it's running ) and at standard conditions is equivalent to a mixture of 93 parts isooctane and 7 parts heptane (by volume).

Lead in the old days delayed the preflame reactions to increase self-ignition temperature/detonation resistance and get octane ratings higher than 100. There are over 500 different hydrocarbons that make up gasoline. While I don't propose to know the "secret" formulas used by gas companies, it isn't a two component fuel comprised of isooctane and heptane.

This is very good except for your statement: "Octane handles compression very well -- you can compress it a lot and nothing happens."
Octane and isooctane are two completely different fuels. Octane (C8H18 also referred to as n-octane, a "normal" or straight chain member of the paraffin family) has an octane rating of -17.
(Ignore the dots, it was the only way I could make everything line up. The vertical lines link the H atoms to the C atoms.)

...H..H.H..H.H..H.H.H
....l...l..l...l..l...l...l..l
H-C-C-C-C-C-C-C-C-H would be Octane C8H18
....l...l..l...l..l...l...l..l
...H..H.H..H.H..H.H.H

Isomers of each normal member of the family have the same chemical formula as the normal member but with different molecular structure and properties. Isomers have the suffix "yl" added. For example, the name 2,2,4 trimethyl pentane is one specific isomer of octane. Tri means three and methyl means the radical CH3. So three methyl groups are attached to the pentane base (5 carbon atoms) at carbon atoms 2, 2, and 4 (numbered left to right) giving:


........CH3....CH3
....H....l...H....l...H
.....l....l....l....l....l
H--C--C--C--C--C--H isooctane C8H18
.....l....l....l....l....l
....H....l...H...H...H
........CH3
This is the structural formula for 2,2,4 trimethyl pentane or isooctane which as you noted has an octane rating of 100. The critical compression ratio of the parrifin family for audible knock in an SI engine decreases rapidly as the length of the chain of the normal members is increased. The normal parrafins in the volatility range of gasoline are poor SI fuels due to very low octane ratings...remember octane has an octane rating of -17. Catalytically cracked fuels have branched parrafins (like above and as you noted) making the carbon chain shorter resulting in higher critical compression ratios.

Again, isooctane not octane. But yes, some combination of fuels that has the same performance (knock characteristics) of a 87/13 combination of isooctane/heptane.

This link provides the other test conditions for MON and RON:
http://www.repairfaq.org/filipg/AUTO...l#GASOLINE_006
You can clearly see the MON is the harsher test and why it always results in a lower number.
If you have time, read through the entire link for some great info:
http://www.repairfaq.org/filipg/AUTO/F_Gasoline.html

Again, very good post.